Starting a home build FG and looking for lots of advice.

[Maninga]

That's a neat looking control unit for the Webasto gear. I'll have to look into it more, getting the internal temperature control using hot water heat exchangers seems a bit finicky.

I plan on using a diesel cooktop for inside, BBQ for outside cooking. Propane is only going to be used for outside kitchen. Aside from the overseas filling aspect, biggest issue here is regulations around having a vent from the camper to outside if you have propane installed. Just seems like a big dust inlet. No propane inside, no need to have vent in the door. But gas is just so much nicer to cook with for many things.

 

[1aquaholic]

I agree pugslyyy and Maninga I can't get away from propane for the outside bbq.

I no nothing about solar and need to start researching but I'm considering using those funny Nuwave cook tops, 1300w on hi and not sure a solar system can support that, but like the idea of storing them and having more counter space also bringing them outside with a extension cord to cook when you want. Thoughts?

Back to water, it would be easy to have a bigger (maybe 5gl) propane tank and a small on demand heater that would run a circuit for the radiant floor and I was thinking of using a very efficient plate heat exchanger for the domestic hot water (shower and sink) placed in the circuit. I could use a use a diesel boiler like the Webasto instead and only use propane for the bbq but I'm a little hesitant because it takes 10 to 20 minutes to get the water up to temp. Again any thoughts would be greatly appreciated.

 

[pugslyyy]

I agree pugslyyy and Maninga I can't get away from propane for the outside bbq.

I no nothing about solar and need to start researching but I'm considering using those funny Nuwave cook tops, 1300w on hi and not sure a solar system can support that, but like the idea of storing them and having more counter space also bringing them outside with a extension cord to cook when you want. Thoughts?

I think you need to bring Diplostrat into the conversation on this one - he started out with a portable induction cooktop and thinking similar to yours but has since changed direction a bit.

 

[LeishaShannon]

I'm considering using those funny Nuwave cook tops, 1300w on hi and not sure a solar system can support that

Thats what we use for cooking and its great being able to cook inside and out with the same appliance and not have to worry about flames going out or gas leaking however it does consume a hefty amount of power. Cooking a few steaks might take 2 minutes to heat up up the pan then a further 8-10 to cook and in that time you'll consume ~300Whr+ of energy from your batteries or ~30 "amps". If you have AGM/lead batteries this may increase to 50 "amps" or so because of that pesky Peukert bloke so you need a decent size AGM battery or look into lithium.

Solar can generate somewhere around 3-4x the name plate wattage on a nice sunny day depending on latitude so just for the steak you'd need a 150W panel...

 

[Maninga]

I've seriously thought about using an induction cooktop also. I've got 800w of solar, getting 400ah 12v Lithium batteries and wouldn't have any concerns about running it. If I was using a 1300w version for 1/2hr, it'd probably around the 60ah level being used (lets assume full power and allow for some losses in the system), expecting the system could easily cope. If it was perfect weather, solar would recharge that in an hour, though figure 2 hours would allow that.

I'm going with the diesel cooktop though, for two main reasons. If I got the cooktop I wanted and quality inverter to suit, price is approaching/passing that of diesel cooktop. It gives a hot plate and warming plate, should do me, and I don't have to get new pans to suit an induction hotplate. I'm getting a 1000w inverter for Nutribullet & Nespresso machine, if I really need another hotplate will bring a cooktop like that along, just keep it as backup and bring some pans from home that don't stack together.

Question on the hot water. What's the rush? Shower might take most of the hot water, but you're not likely to be taking long showers using tank water, heating you can program the heater to come on at certain times or turn it on in advance.

 

[1aquaholic]

Great info on the solar and the convection cooktop thanks a lot! I hope to have a robust solar and inverted if I can afford it, and would buy new cookware ether way. The rush would be that I spend a lot of time in the ocean and am often quite cold when getting out, don't really want to wait 20 minutes. I know it's a first world problem and I would be fine if that was the way it was but if I can make it work the other way without many drawbacks I would like to. The other side of this whole equation is I'm only carrying 15gl of diesel (and 100gl of waste veggie oil). The Webasto only sips .3g/h

 

[mog]

Just to made a point clear on 'induction'. They only require 'magnetic' pans/cookware. So steel, cast iron, magnetic stainless steel, and may composite pans will work. Basically if a magnet will stick to the bottom of the pan/pot/cookware, it will work. No super-duper NASA approved cookware material is required. Also if you have a 'favor' pan you want to use and it is not magnetic, you can use a Mauviel Induction Disc (although those are more $$ then most pans)

 

[pugslyyy]

Question on the hot water. What's the rush? Shower might take most of the hot water, but you're not likely to be taking long showers using tank water, heating you can program the heater to come on at certain times or turn it on in advance.

I find that once you have made hot water, the standard 6 gallon water tank is pretty efficient at staying up to temperature. A "trick" we use is to heat the tank while we are driving down the road. The alternator outputs ~12VDC, which our inverter then converts to 120VAC, which then heats the resistive heating element submerged inside the water tank. It's all horribly inefficient, but it is also pretty much "free" - and doesn't tap the propane reserves.

 

[dlh62c]

.... A "trick" we use is to heat the tank while we are driving down the road. The alternator outputs ~12VDC, which our inverter then converts to 120VAC, which then heats the resistive heating element submerged inside the water tank.....

Once you get where your going and your running off your battery bank, how often does the heating element cycle to maintain the water temperature within the tank?

For example; maybe 5-10 minutes every hour?

 

[Maninga]

Found this interesting when looking into the webasto hot water clorifiers. Gives some descriptions based on their experience.

http://dandjribbans.blogspot.com.au/2008/03/hot-water-system-using-heat-exchanger.html

Drive through the day and use minimal water, should stay hot for a while if out and about

 

[pugslyyy]

Once you get where your going and your running off your battery bank, how often does the heating element cycle to maintain the water temperature within the tank?

For example; maybe 5-10 minutes every hour?

Ah. Once I'm at my destination I switch over to propane. I don't run the electric heater off the batteries.

 

[LeishaShannon]

Once you get where your going and your running off your battery bank, how often does the heating element cycle to maintain the water temperature within the tank?

For example; maybe 5-10 minutes every hour?

For our 24L tank its approximately 400Whr/day , we use a force 10 tank with a 1400W element and an additional 50-75mm of XPS insulation around the tank.

 

[adam88]

I was hoping to build the system around 1400 watts of solar but the roof is only 7 Foot 6 by 14 foot and the most efficient panels that I found I can only get 1250 watts of solar to fit.

Look at Renogy Eclipse 100w solar panels. Just released. They are $219 each and they are much smaller than normal panels because they use high efficiency cells. If your roof is 7.5 feet by 14 feet you would be able to fit 16 panels on it easily. So that's 1600 watts.

 

[SkiFreak]

Yes, but 16 of those panels would be 131kg/290lbs (plus brackets) which is quite a lot of weight to put up on your roof.

 

[adam88]

Yes, but 16 of those panels would be 131kg/290lbs (plus brackets) which is quite a lot of weight to put up on your roof.

Well, gotta pay to play 1600 watts of solar and lightweight will never go together. The flexible panels (which weighed a lot less) were a total bust. They are all being recalled now. I suppose if someone had a lot of money they could create their own panels. Unfortunately lightweight panels just don't exist because the market doesn't exist for them. Homes don't care about weight

That being said, the 290lbs would be spread evenly across the roof. Not the same as a huge stationary weight like a roof top air conditioner or even storage etc.